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I am experiencing an intermittent misfire in #3 cylinder.
The engine will run flawlessly one minute and misfire terribly the next.
Check engine light on, with codes PO154 (insufficient activity from oxygen sensor) and PO303 (misfire in #3}.
Replaced plugs in Cyl 1-3-5, there are no signs of bad plug wires.
The mis continues and is really bad at times.
Any help or suggestions would be greatly appreciated.
Thanks in advance.

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